The way you are required to carry out your work may change from time to time. For example, dramatic changes in technology may require you to learn new ways of working. While it would generally be reasonable for an employer in such circumstances to expect employees to become familiar with the new technology, it would normally be unreasonable to expect you to take on a new way of working without providing you with the appropriate training and support.
If you are asked to carry out work beyond your current competence, then you need to discuss with your manager the type and amount of training and support that will be provided to help you to perform your job effectively.
If no such training and support is proposed, then it might be reasonable for you to refuse to undertake this new area of work.
If you are a member of a trade union, discuss the issue with your union representative. If you are not a union member, then discuss the proposition with fellow workers to see if they have been required to go beyond their competence, and what happened in their case.
If your manager insists that you take on the new area of work without providing adequate training and support, you may wish to take out a formal grievance (in accordance with your organisation's grievance procedure).
